Stem Cell Breakthrough

Two teams of scientists, one in Japan and another in Wisconsin, have solved a medical riddle by producing stem cells for research without destroying human embryos in the process. The discovery may allow scientists to get around ethical concerns about harming human life and unleash greater federal funding. But some experts say researchers should not give up work with tried-and-true embryonic stem cells just yet. Gideon Gil is health and science editor of the Boston Globe.